Improvement in casting cannon



N.FETEE5, PHOTO-LITHOGRAPKER. WASHINGTON. D C.

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JOHN BLAKE TARE, OF FAIRHAVEN, MASSACHUSETTS.

Lette/rs Patent No. 98,894, dated January 18, 1870; antedated January 15, 1870.

`IMPROVEMENT IN CASTING CANNON( l The Schedule referred to in 'these Letters Patent and making part of the same.

To all whom it may concern:

Be it known that I, J ons BLAKE Tann, of Fairhaven, in the county of Bristol, and State of Massachusetts, have invented a newaud improved Gannon; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, making a part of this specification, in which- Figure 1 is a front ele\ ation of a machine which is adapted for the production of the improved cannon. Figure 2 is a transverse section through the machine, taken in the veit-ical plane indicated by red line va; d; in figure 1, showing the follower elevated to its'highest point, to allow metal to be poured into the mould beneath.y

Figure 3 isa simila r section of the same parts shown in fig..2, representing the follower of the machine in 4the act of condensing the metal in the moulds.

Figure 4 is a section through g. 1, taken in the horizontal plane indicated by red line y y.

Similar letters of reference indicate corresponding parts in the several'figures.

This invention relates to a new and improved methed of treating the metal iu the production of cast-metal cannon; and

It consists in subjecting the metal, while in a liquid state, in the mould which is to give it its final shape, 't0 such a degree of pressure as will expel the gases from it, and leave the mass homogeneous in strength, solidity, and toughness, as will be hereinafter explained.

In the production of cannon, mortars, and great guns, of various descriptions of cast-metal, great difficulty has hithertobeen experienced in obtaining castings without serious flaws and other imperfections, and

uit often ihappens that such guns are burst in ordinary usage,"in consequence of imperfections inv the metal which were not discoverable by the tests usually applied to them. Under the most experienced and careful management, there is no certainty that a cannon which is cast under the old processes is free from serious flaws. These flaws, pores, orimperfections, are chiefly caused by confined air or gas which is ent-lapped at various points in the mass in the mould also by the unequal coolingand contraction of the metal.

If the metal be subjected to considerable pressure while it is in a liquid state, and confined in the mould from which it receives the desiredshape, the gases will be expelled from every part of the mass and mould, and, if this pressure be retained until the metal sets, the objection 'above mentioned will not be experienced, and cannon of a given weight may be thus produced,

' which will possess greater strength than cannon of the same weight which are cast by any other process.

'lhe following is a description of one practical mode of carrying my invention into effect:

place thereon, is a cylinder, D, within-which a piston,

E, works; and to'this piston E three guideerods F F F are suitably secured at regular distances apart, around its centre. These rods F pass down through suitable stuffing-boxes, and are secured firmly to a horizontal ring, K, which ring is the follower or prcssing-head for condensing the metal in the mould L, arranged beneath it. Thus arranged, the axis of Vfollower K coincides with the vertical axis' of the cylinder D, and should n'ot deviate from this vertical line in its ascending and descending-movemcnts. v

Beneath the cylinder l), and secured firmly to the bottom of the head-.plate C, is a small cylinder, G, the vertical axis of which coincides with the vertical axis of the cylinder D and follower K; and, within the c'ylinder G, a piston, H, works,'-the rodL of whichextends down through a stuing-box in thehead oifthis cylinder, and is attached, centrally, to the upper end of a core, J, by means of a vtransverse key orv pin, c, as shown in the drawings, figs. l, 2, and 3,1.

The two cylinders I) and G are adapted to be used in connection with a hydraulic press,substantially as described in my Letters Patent of the United States, numbered 67,000, and granted on the (23d) twentythird day ofJnly, 1867.

The mould L, in which the cannons are produced, is supported upon the bed .A of the press, and held down hrmly 'in place by the hooks h h, which are turned over the iianges formed on this mould, as shown in iig. l. This mould L consists of vertical halves or sections, which may be secured together by means `of horizontal bands d and wedges e, or by any otherA i suitable means.

The chamber in this mould is made of the exact size and shape of the cannon which it is desired to produce in it, with this exception: the upper part s s of the chamber is cylindrical, and slightly' larger in diameter than the diameter of the follower K, so that when this follower is within the cylindrical portion of the chamber, as shown in fig. 3, there shall be a space around the follower of sufficient 'size to allow the escape of gas.

The object of making'the upper portion of the chamber of the mould cylindrical is to preserve a uniformity of size ofthe space left between the follower and Wall of the chamber, for the escape of gas during the descent of the follower, which would not be the case if the taper of thechamber was continued to the top of the mould. This4 cylindrical portion 's s should terminate at the point where the descent of the follower ceases, unless it is intended to cut off` a portion of' the muzzle. In practice, the descent of the follower' will cease at the point where the cylindrical chamber s s terminates, so as not to have a snpertlnity of metal in the casting.

In order to prevent a rapid destruction ofthe mould, and to admit of a mould being used for a number of castings, I line or cover the inner surface thereof with a refractory substance, represented in figs. 2 and 3 by the letter c. I also coat the core J with such a substance, and, if desirable, the 'bottom surface of the follower may in like manner' he protected. v

In the selection oa protecting coating for the mouldchamber, the core, and the follower, it is important to employ a substance or compound which will adhere firmly to the surfaces to which it is applied, and which will not expand or contract very much; also, to employ a substance or compound which will not melt and form a slag when subjected to the intense heat ofthe melted metal.

The following method of preparing the mould is found to be best adapted to the end in view:

A core is introduced into the mould, of such size as will leave a space of about one-half or-tln'ee-quartels of an inch between it and the inner wall of the mould, into which space sharp moulding-sand is rammed very hard. This sand is prepared by mixing'wit-h it rye meal and molasses, say, aboutfifteen parts of the sand to one part of a mixture of rye meal and molasses. The mould is then put into an oven, and baked for about twelve hours, after which it is taken out, and its lining coated while hot with a solution composed of about one-part of plnmbago to three parts of' fire-clay, made thin by adding beer to them. After coating the mould repeatedly, and drying each coating, the surfaces are smoothed. The last coating given to the mould should be very tliick, so that it will fill fill up lthe pores in the sand, and leave solid and smooth surfaces.'

The mode of operation tol produce a compressed steel, cast-iron, or alloyed-metal cannon is as follows:

The follower K is elevated to its highest point, to allow space beneath to pour thel metal into the mould, xand the core J is adjusted centrally within the mould, and held firmly in the propel' position to produce the bore in the gun.

Immediately after the mould is filled, or nearly filled, a's the case may be, with melted metal, thefollower is brought down upon it, and all that body of metal vwhich is within the cylindrical portion s of the mould is condensed into the body of metal below it, by the application of great pressure to the follower.

The pressure is retained upon the follower until the metal in the mould sets, aft-er which the pin c is driven out, so-as todetach the core from the piston-rod I, and the mould, with its core, are removed to a suitable place, to allow the metal to cool.

The descent of the follower K and core J will be regulated and determined by the amount of liquid forced into the cylinders D and G, above their respective pistons.

It will be seen, by reference to fig. 3, that during the act of applying pressure to the metal in the mould, there will be an annular space between the follower and inner wall s of the mould, and also an annular space between the core and follower, Vthrough which latter the core passes freely. Through these spaces the gases are allowed to escape from the mould while compressing and condensing the metal therein.

It is important toappl y pressure to the metal in the mould as quickly as possible after the requisite amount has been poured into the mould, and to this end the mould may be constructed with a pouring-tubeor chamber applied on. one side of it, and extending from the bottom of the mould-chamber to the top thereof, at which latter point a cut-off` should be applied, to prevent the escape of metal while pressing.

By thus having a chamber or pouring-hole outside ofthe mould-chamber, the follower may be brought down t'o the proper point for commencing pressure before the mould is filled to this point.

I am aware 'that it has been proposed to condense metal ingots in the casting-process, for the purpose of afterward working them more successfully into the shape of cannon and other ordnance. I also am aware that it has been proposed to give the general exterior form of a cannon in the casting of metal within 'a mould, and at the same time to subject the solid mass of metal to a condensing action; but I am not aware that hollow cannon and other pieces of ordnance have been produced by cast-ing and condensing metal simultaneously. y l

What I claim as my invention, and desire to secure by Letters Patent, is-

1. A cast-metal cannon which has been condensed by high pressure, when in a molten state, and after it has received its general internal and external shape, substantially as described.

2. The combination of the core J with the cannonmould, and with the mechanism described forcondensing the metal, substantially as described.

` J OHN'BLAKE' TARR.

Witnesses: y

JOHN S. HOLLINGSHEAD, Trios. L. BAYLIEs. 

